O-LevelBiologyCoordination & Response5090/21 · May/June 2014 · Q610 Marks
Define the term homeostasis.
- (a)Define the term homeostasis.[2]
- (b)(i)Use the concept of control by negative feedback to explain what would happen in each of the following situations. A person goes outside wearing only short trousers and a short-sleeved shirt on a day when the air temperature is below 10°C.[4]
- (b)(ii)A person drinks an excessive volume of water.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.
- [2] maintenance of/constant ;
- internal environment/conditions within the body ;
- [4] low temperature detected;
- by receptors/sensors on skin ;
- brain;
- any two corrective mechanisms from
- shivering / hairs raised/sweating reduced/stopped/vasoconstriction of blood vessels (R of capillaries) ;;
- temperature rises again;
- [4] (colon) water absorbed into blood ;
- rise/excess (in water content of blood) detected ;
- excess water excreted/removed/more urine produced AW ;
- by kidney;
- correct ref. ureter/bladder/urethra in correct context ;
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